Consolidated Statements of Income - USD ($) shares in Thousands, $ in Thousands		12 Months Ended
		Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Interest income
Interest and fees on loans		$ 693,729	$ 785,241	$ 998,099
Interest and dividends on investment securities
Taxable		37,916	59,806	100,304
Tax-exempt		58,710	58,320	57,565
Other interest		7,833	9,473	16,643
Total interest income		798,189	912,840	1,172,610
Interest expense
Interest on deposits		18,622	67,639	237,286
Interest on federal funds purchased and securities sold under agreements to repurchase		143	485	1,579
Interest on other short-term funding		22	51	138
Interest on PPPLF Funding		0	1,984	0
Interest on FHLB advances		36,493	57,359	69,816
Interest on long-term funding		17,053	22,365	28,116
Total interest expense		72,334	149,883	336,936
Net interest income		725,855	762,957	835,674
Provision for credit losses		(88,011)	174,006	16,000
Net interest income after provision for credit losses		813,866	588,950	819,674
Noninterest income
Noninterest Income In Scope of Topic 606		212,278	246,077	288,247
Capital markets, net		30,602	27,966	19,862
Mortgage banking, net		50,751	45,580	31,878
Bank and corporate owned life insurance		13,254	13,771	14,845
Asset gains, net(a)	[1]	11,009	155,589	2,713
Investment securities gains (losses), net		(16)	9,222	5,957
Gains on sale of branches, net(b)		1,038	7,449	0
Other		11,031	10,200	11,165
Total noninterest income		332,364	514,056	380,824
Noninterest expense
Personnel		426,687	432,151	487,063
Technology		81,689	81,214	82,429
Occupancy		63,513	64,064	62,399
Business development and advertising		21,149	18,428	29,600
Equipment		21,104	21,705	23,550
Legal and professional		21,923	21,546	19,901
Loan and foreclosure costs		8,143	12,600	8,861
FDIC assessment		18,150	20,350	16,250
Other intangible amortization		8,844	10,192	9,948
Loss on prepayments of FHLB advances		0		0
Other		38,721	49,135	53,986
Total noninterest expense		709,924	776,034	793,988
Income before income tax expense		436,307	326,972	406,509
Income tax expense		85,313	20,200	79,720
Net income		350,994	306,771	326,790
Preferred stock dividends		17,111	18,358	15,202
Net income available to common equity		$ 333,883	$ 288,413	$ 311,587
Earnings per common share
Basic		$ 2.20	$ 1.87	$ 1.93
Diluted		$ 2.18	$ 1.86	$ 1.91
Average common shares outstanding
Basic		150,773	153,005	160,534
Diluted		151,987	153,642	161,932
Insurance commissions and fees
Noninterest income
Noninterest Income In Scope of Topic 606		$ 336	$ 45,245	$ 89,104
Wealth management fees
Noninterest income
Noninterest Income In Scope of Topic 606	[2]	89,854	84,957	83,467
Service charges and deposit account fees
Noninterest income
Noninterest Income In Scope of Topic 606		64,406	56,307	63,135
Card-based fees(a)
Noninterest income
Noninterest Income In Scope of Topic 606		43,124	38,605	39,912
Card-based fees		43,014	38,534	39,755
Other revenue
Noninterest income
Noninterest Income In Scope of Topic 606		14,558	20,963	12,629
Card-based fees		$ 17,086	19,238	$ 18,942
Risk Management and Shared Serivies [Member]
Noninterest expense
Loss on prepayments of FHLB advances			$ 44,650

[1] The year ended December 31, 2020 includes a gain of $163 million from the sale of ABRC.(b) Includes the deposit premium on the sale of branches net of miscellaneous costs to sell. See Note 2 Acquisitions and Dispositions for additional details on the branch sales.

[2] (a)